add FAQ entry to diagnose differences between query result and FS

This entry provides simple steps to verify whether excluded search
tags are the cause of the discrepancy between the list of emails on
the file system and the result of a query with folder search term.

diff --git a/faq.mdwn b/faq.mdwn
index 7e41e961b576e79a6c405d626d5a5937b6869c8d..652d33015b4afe427bec0784d36a43c6a3b1b306 100644 (file)
--- a/faq.mdwn
+++ b/faq.mdwn
@@ -12,6 +12,19 @@ with the same message (i.e. the files have identical Message-ID). A
 `folder:` search will match the folder of any of the files. The
 `--output=files` option outputs all the files of all matching messages.
 
+## How come this query does not list all the emails on the file system? `notmuch search --output=files -- folder:inbox`
+
+You may have emails that only have some of the excluded tags.
+
+Notmuch can be configured to exclude some tags while searching. You can list excluded tags with
+
+       $ notmuch config get search.exclude_tags
+       deleted
+
+To verify this is the reason of the discrepancy, add the excluded tags explicitly to your query.
+
+       $ notmuch search --output=files -- folder:inbox tag:deleted
+
 ## Shouldn't notmuch support inline PGP?
 
 [Why it might not be a good idea](https://dkg.fifthhorseman.net/notes/inline-pgp-harmful/)